There is a printed circuit board mounting shelf in which guide portions of a sectional concave shape are arranged in parallel by being positioned to oppose to each other on an upper side and a lower side of the shelf, and a tip of the lower side guide portion is positioned in front of a tip of the upper side guide portion at the time of inserting a printed circuit board.
Moreover, there is a housing structure in which a conductive tongue-shaped piece is arranged in a housing, and the conductive tongue-shaped piece protrudes between grooves of the housing so as to be in contact with a conductive metal piece which is connected to a predetermined signal line within a plug-in unit at the time of the insertion.
Furthermore, there is a structure in which a braking portion is provided in an auxiliary rail of a shell portion such that a slide accommodation speed of a plug-in rail is reduced.
Japanese Laid-open Patent Publication No. 7-212063, Japanese Laid-open Utility Model Publication No. 61-129395, and Japanese Laid-open Patent Publication No. 2011-181568 are examples of related art.